The types of evidence that are used in local decision making, including the policy process, extend beyond research to encompass politics, economics, stakeholder ideas and interests, and general knowledge and information (see Chapter 3), and the decision maker needs to take a practical approach to incorporating this evidence into real-life challenges. Working from this expanded view of what constitutes relevant evidence and where to find it (Chapter 5), this chapter describes an approach for evaluating these different types of evidence that is dependent on the question being asked and the context in which it arises.
Before proceeding, it is worth emphasizing that the L.E.A.D. framework is useful not only for decision makers and their intermediaries but also for those who generate evidence (e.g., scientists, researchers, funders, publishers), a point captured by the phrase “opportunities to generate evidence” surrounding the steps in the framework (Figure 6-1). In fact, a key premise of the L.E.A.D. framework is that research generators need to give higher priority to the needs of decision makers in their research designs and data collection efforts. To this end, the use of the framework and the evaluation of evidence in the appropriate context will identify gaps in knowledge that require further investigation and research.
This chapter begins by reviewing several key aspects of the evaluation of evidence: the importance of the user perspective, the need to identify appropriate outcomes, and the essential role of generalizability and contextual considerations. After summarizing existing approaches to evaluating the quality of evidence, the chapter describes the general approach proposed by the committee. Finally, the chapter addresses the issue of the trade-offs that have to be made when the available evidence has limitations for answering the question(s) at hand—a particular concern for those who must make decisions about complex, multilevel public health interventions such as obesity prevention.
The approach of “horses for courses” (Petticrew and Roberts, 2003) emphasizes that what constitutes best evidence varies with the question being addressed and that there is no value in forcing the same type of evidence to fit all uses. Once the question being asked is clear, users of the L.E.A.D. framework must either search for or generate (see Chapter 8) the kinds of evidence that will be helpful in answering that question. The next chapter describes how to assemble the evidence to inform decisions. For situations in which the evidence is inadequate, incomplete, and/or inconsistent, this chapter suggests ways to blend the best available evidence with less formal sources that can bring tacit knowledge and the experience of professionals and other stakeholders to bear.
A large number of individual questions can, of course, be raised by those undertaking efforts to address obesity or other complex public health challenges. Petticrew and Roberts (2003) place such questions into eight broad categories: effectiveness